A novel three-stage foam separation technology for recovering sodium dodecylbenzene sulfonate from its wastewater

• A novel technology was developed to treat the surfactant industrial wastewater.
• The synergistic effects of temperature and foam separation column were studied.
• Recovery of a surfactant at a high concentration from its wastewater was studied.
• The recovered SDBS could be used as a raw material to produce SDBS products.

Foam separation is one of the most economic and effective technologies to treat wastewaters. However when a surfactant concentration is equal to or more than its critical micelle concentration (CMC), its enrichment ratio will greatly decrease, significantly affecting its application to industries. So a novel three-stage foam separation technology was developed to intensify the process of recovering sodium dodecylbenzene sulfonate (SDBS) at a high concentration from its wastewater. The first, second and third stages of the technology aimed at increasing the SDBS enrichment ratio and recovery percentage, and decreasing the SDBS concentration in the residual solution, respectively. The synergic effects of temperature and a column of intensifying foam drainage were studied in order to enhance the enrichment ratio. By the three-stage foam separation technology, the enrichment ratio and recovery percentage reached 26.3 and 99.0%, respectively and the SDBS concentrations in the residual solution and in the foamate were 4.304 × 10−5 mol/L and 0.0981 mol/L, respectively.

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